Yamaha YZF-R125 Quiz
Electrical system

Checking the rectifier/regulator

In this manual: Electrical system
General information — 15Specifications — 14Periodic checks and adjustments — 41Chassis — 67Engine — 76Cooling system — 12Fuel system — 10Electrical system — 61Troubleshooting — 13
~1min read

1. Check:

Rectifier/regulator output voltage Out of specification → Replace the rectifier/ regulator.


a. Set the engine tachometer to the spark plug lead.

b. Connect the pocket tester (DC 20 V) to the rectifier/regulator coupler as shown.


  • Positive tester probe
    red "1"
  • Negative tester probe
    black "2"
Checking the rectifier/regulator

c. Start the engine and let it run at approximately 5000 r/min.

d. Measure the charging voltage.

Test yourself

A quick Yamaha YZF-R125 quiz: every answer comes with an explanation and a link to the manual page.